This invention relates to electrical devices and more particularly to an electrical power cord entry device that provides a fluid tight joint between the electrical device and the cord.
Many electrical devices receive electrical power by having a cord or cable connected to a plug, which is inserted into an electrical socket.
Typically the cord or cable has a covering to protect the cord or cable against the accumulation of moisture and against corrosion. In general, the outer jacket of a cable will be waterproof in the way that a garden hose is waterproof. Water will not penetrate the jacket under normal conditions but will be carried along the length of the cable if it enters at the end of the cable or through a break in the cable jacket.
If a cable is to be used underwater or in a severe moisture environment, and one end must enter a sealed device which is underwater or in the wet environment, a means must be provided to keep water or moisture from entering the device and the cable at the point of entry of the cable. A molded cord end will isolate interior and exterior environments from each other and prevent wicking by the insulation in the cord. If the cable is reasonably round and firm, a packing gland may be used. Sealing compounds are often used in conjunction with the packing gland to obtain a tight mechanical seal.
The prior art obtained a double seal by using castings and stripped leads together with a potting compound. One of the difficulties with the above process was that the process was labor intensive and hence expensive.
Reference may be had to the following patents for further information concerning the state of the prior art.
U.S. Pat. No. 4,481,697 issued Nov. 13, 1984 to Walter N. Bachle and assigned to the assignee of this application discloses a body member, a grommet, a strain relief member and a nut. Tightening the nut onto the body member results in radial forces between the grommet and the cord to restrain the cord and provide a water tight seal. The grommet is stuffed into the body member by an interaction between the grommet and the strain relief member as the nut is engaged with the body member.
U.S. Pat. No. 3,891,294 issued Jun. 24, 1975 to Robert A. Phillibert and assigned to the assignee of this application discloses a two part clamping device that is adapted to fit within a locking collar that is used at the outer end of a connector. The Clamping device is provided with suitably designed flanges that can be inserted through an aperture and into the interior of the locking collar from the outside. A pair of ears, for each of the clamping device parts, extend radially outwardly from either side thereof, such ears lying in a plane which passes near the longitudinal axis of the clamping device. Each of such ears is provided with a screw receiving hole, and a pair of screws are used to bring the two parts of the clamping device together, so as to clamp or grip the cable or cord.
U.S. Pat. No. 4,350,840 issued Sep. 21, 1982 to Leonard H. Michaels discloses a compression chamber with a distortable grommet which has independent gripper elements that are socketed into the grommet so that the gripper elements perform a compound closing action on the cord with the result that the cord grip has great flexibility as to the range of sizes and types of cords it will accept.
U.S. Pat. No. 4,549,038 issued Oct. 22, 1985 to Fred Masherls et al. discloses a cord grip that contains a compression chamber with a distortable grommet which has gripper elements associated therewith so that the gripper elements perform a closing action on the cord in response to reduction in the volume of the compression chamber.